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23

Unfortunately, we are all still "confuzzled" by how memory works. We are far from a complete understanding of how memory is stored and recalled. Nonetheless, we do know a little, so read on. Your understanding of basic neural function is almost correct. First, an individual neuron will signal through its single axon onto the dendrites of many downstream ...


12

You would need to live a long, long, long, long time for this to become remotely problematic. Your question seems to suppose that a memory is "stored" by a neuron, and since neurons have mass, then the more memories we have the more our brains will weigh. Actually, neurogenesis is pretty rare in the adult brain--most of the cortex is fixed, and new neurons ...


11

Its not clear that this is true. Working with animals has been a little disconcerting over the past 50-60 years. In the distant past, I think most evolutionary anthropologists and their like bought into the idea that humans were completely uniquely intelligent and spiritual. But the more we try to define human sensibilities apart from other animals, the ...


7

Well, Erickson et al (2011) attribute the increase in brain volume in the aerobic exercise group to brain-derived neurotrophic factor (BDNF). Specifically (p. 3020): In fact, we found here that changes in serum BDNF levels were associated with changes in anterior hippocampal volume; an important link because the hippocampus is rich in BDNF, and BDNF ...


7

The newest and most accurate method (far more accurate than older extrapolating/manual counting methods (Stereology) and yielding some surprising results) to estimate number/density of neurons/cells in brains is Isotropic Fractionator to my knowledge. Using this keyword you find some recent papers, comparing different brain areas (cerebral cortex, ...


6

I would like to point out some ways your understanding is wrong. "Neural networks" are usually a computer science term, only very, very loosely based on actual neural networks. The idea of layers in a neural network is pretty much an invention of computer science, it doesn't really reflect the reality. Also, neurons are not binary switches. It isn't so much ...


6

Although tinnitus is usually described as a ringing in the ear, there's a whole range of tunes, buzzes, whooshing sounds, humming and hissing sounds that are described of as tinnitus. The sounds can either genuinely be there or be perceived to be there. If it is genuinely there it suggests muscles ate at play or some blood vessel disease if the sounds are in ...


5

One of the many advantage of an all-or-none system is that resources can be conserved for timing events that require synchronized collaboration between many cells (like locomotion). Binary behavior may also partially be a side effect of speed and efficient long-distance information transfer (which is one of the great advantages of neurons as cells in the ...


5

I haven't read anything particularly about dendrites being reshaped, though I would expect them to be as flexible as other parts of the cells. The more commonly discussed topic (in my literary experience) is reshaping of the axon's branches before forming synaptic terminals. These branches are not fixed even in adults - neurons can grow new and retract old ...


5

As you say, a neuron can have thousands of inputs via its thousands of dendrites. Each of those dendrites can have a synaptic connection to the (axonic) output of a different neuron. So the neuron can take inputs from thousands of different neurons, not just from one other neuron. At the other end of the neuron, the output of the axon can form synaptic ...


4

Microtubules are a structure in the cytoskeleton, they are rope like polymers that grow to a length of about 25 micrometers (25000 nm), and have an outer-diameter of around 25 nm. For comparison, the mean spacing between atoms is on the order of 0.1 to 0.2 nm; so the micro tubule really is micro: about 200 atoms across. In terms of quantum effects though, ...


4

I would say no. You question somehow implies that somatosensory cortex is equally distributed among the different sensory areas of the body, whereas in the reality this is the known "cortical homunculus" concept of how this distribution looks: If you look at this representation you'll see that chest and legs take only about one third to one fourth of the ...


4

Mechanical force can compress neurons and cause action potentials as you probably experienced in the form of hitting the funny bone. Strong enough acceleration of the brain tissue may be causing massive excitation of neurons as indicated by animal EEG study. It suggests that the loss of consciousness is due to generalized epileptic seizure. However, it is ...


4

+1 for giving a solid answer to @AP, but being older I've had friends who have had tinnitus and I'd like to add some notes to try to flesh this out a bit. I don't think tinnitus is the result of nerve damage usually. Nearly everybody experiences episodic tinnitus at one point or another. When exposed to a loud sound or a blow to the head can cause it. ...


3

I think that the advantages of using both hands with equal ease is quite evident whether it be sports, at your work or while you are doing your household chores. An obvious advantage is using both hands to write or draw with both at the same time. I would be focusing on the disadvantages that may be faced. 1) Ambidextrous people are more prone to ...


3

Its pretty well established that there are photoreceptors in cells besides the cones and rods in the retina of the eye. Humans and most animals have four light receptor genes known (so far). In addition to Rhodopsin - there are the short, med and long wavelength opsin genes. While they are mostly expressed in the retina of the eye, they can be found in ...


3

There are a number of different wiring scenarios that could lead to this type of behavior, even in a dissociated neuronal cell culture. The two major cases are neurons that are truly isolated from each other, and collections of neurons that connect together. Since your question refers to firing and synchronized bursts, I'll restrict my discussion to the ...


3

I've found a rough answer myself: The globe of the eye, or bulbus oculi, is the eyeball apart from its appendages http://en.wikipedia.org/wiki/Globe_%28human_eye%29 ... the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the ...


3

I think is closer to 2. It is the subset of sensory space that elicits a reaction in a given neural population. So you should: Pick your neural population. Usually it is a single neuron (but can be easily extrapolated to bigger populations). It may be a sensory neuron, or a neuron in a higher processing region. Determine your sensory space. That is, you ...


3

You are completely right with your guess that is was Ramón y Cajal who first described these cells in his famous monograph "Histologie de systeme nerveux de l'homme et des vertebres." published in Paris Maloine in 1911. Since the only method he had at his disposal was Golgi's staining which is a pure anatomical staining (there is no living cell left in the ...


3

Even if it were possible to selectively destroy sensory (afferent) nerves alone, the individual would not be able to walk/move normally immediately afterwards, because there would be no environmental stimuli with which to orient one's actions. Two of the senses people often overlook are balance (or spatial orientation) and proprioception (where the body ...


2

As you've already mentioned, cells near the primate macula tend to make one to one connections. Due to this lack of convergence they can be somewhat smaller than normal cells (particularly in the size of their dendritic arbors) earning them the moniker "midget" ganglion and bipolar cells (also P cells). By reducing the magnitude of photoreceptor ...


2

I do not have a source for the following as it was taught to me in neuroanatomy classes, the explanation given for brain freeze is that it is referred pain through the trigeminal nerve. The meninges (the tissue lining the central nervous system) is innervated by the trigeminal nerve in the head. Therefore the pain feels as though it is like a headache from ...


2

One thing I think you're missing: a perceptron model and a spiking model aren't mutually exclusive. In fact, in perceptrons, people usually use a sigmoid function. That's not a coincidence: it kind of simulates a spike. If you were to model an organism such as C. elegans, whose neurons aren't spiking (but use "graded action potentials"), you would use ...


2

A LFP can be measured at any point in space and is just the sum of all the fields generated by nearby charges. Conventionally, it's assumed to be some distance from a cluster of neurons, but you technically could measure the LFP near the external surface of a neuron (but that would bias your signal towards the reading of that one neuron). LFP's are ...


2

When our brain works out where a part of our body is in relation to another part of our body, or in relation to anything for that matter, we combine: visual information information about how much our muscles are contracted how much our joints are contracted different forces being applied on our arms/legs or other body parts where it remembers we used to be ...


2

The situations you describe involve what is called proprioception or the feedback to the brain of where your arms and limbs are in space. As APengioun mentioned, this is a complicated undertaking and if information is restricted, for example eyes are closed then the sense of where your limbs are gets messed up. As for your title, it's not really neuronal ...


2

The optic nerve fibers cross inside the optic chiasm sharing the same shell: The crossing fibers go ones between others, like on this classical picture -


2

It probably depends on what stage of development the neurons are in and what region of the brain. If there's not branching still going on, then probably not. Hebbian learning is generally considered a concept of neuron connections strengthening (more synapses forming and dendritic spines growing larger) and not the initial formation, particularly in ...



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